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HL: Fachverband Halbleiterphysik
HL 81: Focus Session: Extended defects in semi- and nonpolar GaN II
HL 81.7: Talk
Thursday, March 14, 2013, 16:30–16:45, H13
Correlation of microscopic optical properties and defect structures of semipolar GaN on pre-patterned sapphire substrates by cathodoluminescence — •Sebastian Metzner1, Frank Bertram1, Thomas Hempel1, Tobias Meisch2, Stephan Schwaiger2,3, Ferdinand Scholz2, and Jürgen Christen1 — 1Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg — 2Institute of Optoelectronics, University of Ulm — 3now with OSRAM Herbrechtingen
Spatially and spectrally resolved cathodoluminescence(CL) microscopy has been used to analyze the local luminescence characteristics of semipolar (11-22)GaN stripes grown out of trenches exhibiting c-plane-like sapphire sidewalls. The micro structure has been etched into a (10-12)sapphire substrate yielding an inclination angle of 58∘ towards (0001)sapphire which enables a planar semipolar (11-22) surface for the coalesced triangularly shaped GaN stripes. Local CL spectra reveal a distinct contribution of structural defects like basal plane stacking faults(BSF), prismatic stacking faults(PSF), and partial dislocations(PD) to the CL emission at the region where the GaN is grown into -c direction after leaving the trench. In complete contrast, the main part grown into +c exhibits pure donor-bound exciton emission interrupted by bundled and bended threading dislocations. Due to a delayed coalescence process the defect structures run into a void and, thus are prevented from propagating further through the coalesced layer. The optical properties of InGaN QW structures grown on top of this SF-free semipolar GaN surfaces are going to be discussed.